Removal of objectionable organic sulphur from isopropyl and higher secondary alcohols



March `26, .1935. F ARQ-"BALB ET AL 1,995,597'

NIC SUL RE AL. oF'o GT ABLE oRGA PHUR FROM OPROPYL AND HER SECONDARYALCOHOLS Filed July 29, 1932 :11 "HI Him Recycled distillate PatentedMar. 26., 1935 REMOVAL F OBJECTIONABLE SULPHUR FROM-ISOPROPYL ALCOHOLSSECONDARY Francis M. Archibald and Clayton M.

Elizabeth, N.

Company Beam J., assgnors to Standard Alcoh ORGANIC ANnmGnEn el', ol

Application July 29, 1932, Serial No. 625,786

d Claims.

This invention relates to a method of removing objectionable sulphurcompounds from isopropyl and higher secondary alcohols.

More

particularly it relates to the removal of mercompounds.

other sulphur Secondary alcohols are manufactured by esterifying thelower boiling point petroleum oils with sulphuric acid, separating theacid liquor fro rated acid vliquor alcohols by steam m the petroleumoils, hydrolyzing the sepaand recovering the resulting distillation.'I'hese alcohols are characterized by pronounced color and disagreeableodor due to sulphur compounds present.

An object of this invention is to remove the sulphur compounds thatimparta pronounced color and disagreeable The invention will be odor tothe alcohols. fully understood fromthe following description taken inconnection with the accompanying drawing in which the iigure isadiagrammatic view of the invention:

Referring to the dra a mixing tank. Mix taining objectionable ample,about .300% storage not shown showing the preferred form l' wing,numeral 1 indicates ed secondary alcohols consulphur compounds, for exofsulphur, are passed from through pipe 2 into tank 1. containingobjectionable sulphur compounds, for example about .318% sulphur, ispassed into tank 1 by means of pipe 2a. The sodium plumbite solution,prepared by adding about 60 parts of litharge to about 125` parts ofsodium hydroxide dissolved water, is passed from hopper in 1000 parts of2b through pipe 2c arranged with valve 2d into mixing tank l. 'Ihemixture in tank 1 is contacted by continuously withdrawing a portion ofthe mixture through pipe 5 by means of pump 6 and returning it throughpipe 7 and spray pipe 8. 'Ihe mixture in tank 1 may also be contacted byagitating with air by passing air into tank 1 bymeans of pipe 3,arranged with'valve 4. An air vent pipe 7a arranged with pressure reliefvalve 1b is used to regulate the pressure in tank 1. Both or either oneof the mixing means may be used at the same time, though it is preferredto mix by recirculation, air,` some of the as when mixed by blowing withlighter alcohol vapors are lost. A `separatory tank 9 is connected withtank l by means of pipes 10, 12 and 14 arranged with After the sodiumplumbite een continuously vcontacted valves 11, 13 and-15. and alcoholshave b for about two hours separatory tank .9. Upon opening the `valves11, 13 and and sodium plumbite solution added to tank tinuously added15, more alcohol are continuously The quantity of alcohol conis governedby the amount passed from the separatory tank 9 to the distillationcolumn 21. Only a small amount of sodium plumbite is added. as the rstcharge of sodium plumbite period of time providedon Ipipe dium plumbitesolution from tank tory-tank 9 especially when the is spent and itsystem and ad Tank 9 is provided at the bottom with a valved treatedalcohol.

outlet Sato remove the spent sodium plumbite.

provided in tank 9 above which pipe 1.7 1S

-The treated alcoholis passed by means of pump 18and pipe 19 arrangedwith valve 20, to an- The rectlfying column 21.

intermediate vided with ar closed steam coil 22 at the bottom tovaporize the plates orothe The alcohols o a fraction ofthe alcohols andthe usual vapor-liquid contacting means. being heated are vaporized andalcohols together with the lighter boiling mercaptides are passedthrough pipe 23 to condenser passed through densate passing two parts,one

to column 21 by means of pipe 27 24 where they are condensed and pipe 25toweir 26. .'Ihe oonthrough weir 26 is divided-into portion beingreturned as reiiux and valve 28,

another portion being passed through-pipe 31 arranged with Weir 32.

valve and then into a second The quantity of reflux returned to column21 is regulated by vmeans of valves 28 and 30 and overflow pipe 29arranged in weir 26 and is generally about 8 parts to 1 The remainingvportion of the part or greatcondensate is passed from weir 32 throughpipe 33 into decanter 34. Decanter 34 is arranged with a balde 36 at theinlet from pipe 33 'and a outlet 35 arranged with a valve U-tube bottom35a which is used to remove the water that may separate in the lowerpart.

alcohol heads canter 34 and this alcohol Pipe 37 is used to withdraw thefrom the upper portion of demay be passed through pipe 2a into tank 1 or'tostorage not shown. The

withdrawal of of valves 38 and 39- and the condensate is generally4higher than that oi' the initial alcohol used in tank 1, they areallowed f to iiow by gravity into in column 21 this alcohol is regulatedby means the sulphur content of in the process.

The condensed 'portions of the alcohol present on the second, third andfourth used to withdraw the' bell cap' A sulphur, and they are and maybe removed by means of pipes 40, 41 and 42 arranged with valves 43, 44and 45 to alcohol is withdrawn from cooler 46 through pipe 47 arrangedwith valve 48 to 'weir Ibox 49 and through pipe 50 to storage not shown.The plates from which the condensate is withdrawn are regulated by meansof valves 43, 44 and 45 and the sulphur content of the finished productis found to be materially reduced, for example, to .152% sulphur. Thebottoms present in column 21 contain the high boiling mercaptides andare generally high in sulphur, for example, .64% withdrawn by means ofpipe 51 furnished with operating this column about 15% low boilingalcohols and mercaptides are removed as overhead condensates, about 25%removed as higher boiling alcohols and mercaptides from the bottom ofthe column and about 60% removed by the side streams as purifiedalcohols.

The mixed alcohols used for the illustration were of a wide boilingrange. If another mixture of alcohols of a narrower boiling range wastaken, the percentages recovered as overhead and bottoms would be agreat deal less and more puried alcohols would be recovered through .theside streams.

If desired, a second column may be provided into which the purinedalcohol recovered throughl streams 40, 41 and 42 may be passed and thealcohol further rectified under similar conditions as in column 21 to.further reduce the sulphur content. This process may be operated eitheras intermittent or continuous. If desired to operate continuously, anumber of mixing tanks similar to tank 1 may be provided and while thealcohol and sodium plumbite are being mixed in one tank, another mixtureof the two solutions may be separated in a tank similar to separatorytank 9.

In the example disclosed, alcohols of definite sulphur content wereshown but this is not intended as a limitation as they were given onlyfor illustration.

The foregoing description is merely illustrative and alternativearrangement may be made within the scope of the appended claims in whichit y 1,995,597 plates from the top are of low sulphur content valves 52and 53. In

' is our intention to claim all novelty as broadly as the prior artpermits.

We claim: Y v 1, The method of purifying secondary alcohols containingsulphur compounds, which comprises contacting secondary alcoholscontaining sulphur compounds with a water `solution of sodium plumbite,separating the secondary alcohols from the sodium plumbite solution,subjecting the separated secondary alcohols to rectification andseparately withdrawing liquid fractions -of the puriiled secondaryalcohols and vapor fractions of the secondary alcohols containingsulphur compounds.

2. The method of purifying secondary alcohols containing sulphurcompounds, which comprises contacting secondary alcohols containing.sulphur compounds with sodium plumbite solution for about two hours,settling the mixture of secondary alcohols and sodium plumbite intolayers, separately withdrawing the secondaryalcohol layer and the sodiumplumbite solution, subjecting the separated secondary alcohols torectincation and separately withdrawing liquid fractions of the purifiedsecondary alcohols and vapor fractions of the secondary alcoholscontaining sulphur compounds.I

3. The method of purifying secondary alcohols containing sulphurcompounds in solution, which comprises contacting secondary alcoholswith a water solution oi` sodium`plumbite, separating the secondaryalcohols from the solution of sodium plumbite, passing the separatedsecondary alcohols to a rectification zone, separately withdrawingfractions of the secondary alcohol vapors containing the lower boilingpoint sulphur compounds, condensing the said vapors, returning afraction of the condensate to upper part of the rectifying zone andwithdrawing separate fractions of the purified secondary alcohols and ofthe vsecondary alcohols containing the higher boiling sulphur compounds.

4. The method of purifying secondary alcohols containing sulphurcompounds in solution according to claim 3 in which apart of thecondensate is contacted with a water solution of sodium plumbite,separated from water solution of sodium plumbite andrectiiled.

FRANCIS M. ARCHIBALD. CLAYTON M. BEAMER.

